This invention relates to an improved laser apparatus and method employing a single laser and a sequence control device for removal of hair, or veins or capillaries, and more particularly, it relates to a single laser emitting a series of sequential pulses of coherent light energy, which are transmitted to the same area of the skin through a common optical delivery system.
Hair removal by lasers is a new clinical field developed in the early nineties and only commercially available to patients since 1996. Lasers allow the rapid removal of large areas of hair, veins or capillaries on almost any body area, such as on the face, arms, legs, breasts, hands, stomach and the like. Laser treatment provides an unusually low discomfort level to the patient, and hair removal may last for weeks on a body area. However, all of the current lasers used for hair removal are problematic and produce unwanted side effects such as burning the skin, changes in skin pigmentation, and sometimes permanent scarring.
The currently available lasers use different approaches to hair removal, and use different laser technologies. For example, the ND:YAG laser was the first commercially available laser, but is the least effective, and does not provide permanent hair removal. The ruby laser emits a fixed wavelength of 694 nm, but has a propensity to burn the skin of the individual being treated. Because of this problem, ruby lasers cannot be used to treat olive-skinned or tanned individuals. The alexandrite laser emits a fixed wavelength of 755 nm (near the infrared spectrum), but has a propensity to burn the skin of the individual being treated, and is less effective than ruby laser treatment. Also, lasers presently being used do not consistently and reliably provide permanent hair removal, they require multiple treatments, and often burn the skin.
Pulsed flashlamps emit filtered visible light having wavelengths in the range of 550 nm and above, but have not been effective in providing permanent hair removal.
Current cutaneous lasers work by delivering energy in the form of laser light which is absorbed by the cutaneous target, heating the target and thereby causing its destruction. Different skin structures have different colors, different surface to volume configurations, and other factors which cause differential rates of heat loss. All of the hair removal lasers work by application of the principal of selective photothermoloysis, i.e. selective destruction due to heat caused by absorption of light. Laser light, which has a single wavelength, is optimally absorbed by a target which has a complementary specific color. This laser target is called a chromophore. The usual chromophore for hair removal lasers is melanin, found in high concentration in brown and black hair, and is responsible for the color of hair.
The clinical problem is that melanin is also found in the epidermis, and is responsible for native skin color and tan. Laser energy is therefore also absorbed into the epidermis. The problem of hair removal by lasers therefore is to deliver laser energy that heats the hair to a sufficient degree to cause permanent damage and hair loss, yet spare the skin of any damage. Present lasers are unable to accomplish this. For example, ruby lasers work in removing hair follicles because the wavelength of 694 nm which is emitted, is selectively absorbed by melanin and less so by other cutaneous structures, such as blood vessels. In fair skin, with little melanin, selectivity is sufficient to allow sparing of the skin and destruction of hair with even a single pulse. Alexandrite lasers perform similarly, but since their absorption by melanin is somewhat lower they seem to be less effective than ruby lasers, at least in their current forms.
The Cynosure(copyright) laser adds another approach, which they call Thermokinetic Selectivity(trademark). This means the selective destruction of the target with the same chromophore as the skin (i.e. melanin), due to less efficient heat conduction out of the hair (as compared with the epidermis). This less efficient heat conduction is due to a variety of factors, the main one being the unfavorably large volume to surface area of the hair. The Cynosure(copyright) laser, like the ruby lasers, uses a single pulse, but the pulse used by this alexandrite laser is longer (5-20 ms). This longer pulse allows more gradual accumulation of heat by the skin, so the heat has time to dissipate (cool) and to prevent burning of the skin. This technique improves safety, but the technique is not able to deliver enough heat to provide permanent hair loss, and some burns still occur.
The use of medical lasers to produce permanent hair removal in patients with hairs of all colors, and skin of all colors, has, up to this time, been impossible to achieve with current technology. While promising, the currently-used lasers have all been unable to treat patients with dark skin. In addition, even in Caucasian patients, the currently-used lasers have burned many patients, leading to prolonged changes in skin color and even, in some cases, to permanent scarring. Hair loss, although usually prolonged, has not been permanent for the majority of patients.
Nevertheless, the use of monochromatic (laser) light in the range of 694 to 900 nm still appears to be the most effective way to achieve long-term hair removal. To achieve predictable permanency we need to achieve higher temperatures in the hair without heating the epidermis to the point where it is burned. The single pulse techniques described above are inadequate to accomplish this.
There remains a need for an improved laser apparatus and method which will supply a series of laser energy pulses with short time delays between pulses to heat a hair follicle sufficiently to cause permanent damage to that hair follicle, and yet spare the skin from burning, thus providing a safe and permanent method of hair removal.
A new laser has been developed that has the following major advantages: 1) increased efficacy, causing greater hair loss and true permanent hair removal; 2) increased safety, with burning of the skin eliminated, so that treatment has no side effects; 3) increased speed of treatment, nearly by a factor of two; and 4) it allows the use of laser hair removal for patients with dark skin, thereby greatly increasing the range of people who can be treated with this technology.
Laser apparatus and methods for hair removal having various structures have been disclosed in the prior art. For example, U.S. Pat. Nos. 5,630,811 and 5,658,323 to Miller disclose a method and apparatus for dermatology treatments for lesions and hair removal using a modified laser device. The specific target for the laser radiation is the melanin within the hair shaft and within the melanocytes lining of the follicular duct. Pulse width is controlled to provide a direct thermal effect from a single pulse.
U.S. Pat. No. 5,647,866 to Zaias discloses a method of hair depilation through the application of pulsed laser energy having a wavelength readily absorbed by hemoglobin. The process of selective photothermoloysis is used by the laser to focus on a particular region in the epidermis to be irradiated. The pulse duration or time period (30 to 40 nanoseconds) is shorter than the thermal relaxation time for melanin in hair.
U.S. Pat. No. 5,683,380 to Eckhouse discloses a method and apparatus for removing hair (depilation) using a single high intensity pulsed flashlamp (not a laser) which emits a broad spectrum of pulsed incoherent light that is polychromatic. Because of the broad spectrum of wavelengths emitted by the flashlamp, only part of the light energy is absorbed by the hair, making it inefficient for permanent hair removal, although it does provide temporary hair loss.
None of these prior art patents disclose the particular structure of the present invention of a laser apparatus and method using a single laser and a sequencer for safe and permanent hair removal.
Accordingly, it is an object of the present invention to provide an improved laser apparatus and method which supplies a series of pulses of laser energy with short delays between the pulses from a single laser to heat a hair follicle and hair follicle shaft to cause permanent damage to that hair follicle and shaft, and yet spare the skin from burning, thus providing a safe and permanent method of hair removal.
Another object of the present invention is to provide an improved laser apparatus employing a single laser, controlled by a sequence control device, and a fiber optic cable which sequentially emits a series of pulses of coherent light energy from the fiber optic cable for permanently removing a plurality of hair follicles, veins or capillaries from the skin area of a patient.
Another object of the present invention is to provide an improved laser apparatus having a handpiece for ease of use by the operator in directing the series of laser pulses at the skin to rapidly remove large areas of hair on almost any body area, such as on the face, hands, arms, legs, breasts, stomach and the like, where such treatment provides a low discomfort level to the patient.
Another object of the present invention is to provide a single pulsed laser and a sequence control device for emitting laser energy through an optical delivery system which delivers a series of sequential pulses from the single pulsed laser.
Another object of the present invention is to provide an improved laser apparatus and method for treatment of other cutaneous conditions (in addition to hair), such as the treatment of leg veins, spider veins, angiomas, lesions, other vascular anomalies and other dermatological conditions effecting the skin of a patient.
Another object of the present invention is to provide an improved laser apparatus and method for adjusting the numbers of pulses, the pulse width, the time delay between pulses, and the energy level of each pulse, to customize treatment and the energy delivered to the spot being treated according to skin color, hair color, hair diameter and the anatomic site being treated.
Another object of the present invention is to provide safe and permanent hair removal in a wider range of patients having hairs of all colors and skin of all colors, including patients with dark skin. Generally, the present invention will accommodate all persons having hair which is darker than their skin.
Another object of the present invention is to provide a delay between laser pulses which is much shorter than the thermal relaxation time of the hair being treated, so the hair does not cool off between pulses.
Another object of the present invention is to provide a method and apparatus wherein the delay between laser pulses is so short that less energy has to be transmitted to the hair to cause permanent hair loss.
Another object of the present invention is to provide an improved laser apparatus and method that is easy to use, and the laser apparatus is durable, light-weight and easily maintained.
Another object of the present invention is to provide an improved laser apparatus that provides a wider beam area (spot size on the skin) by utilizing a single pulsed laser and a sequence control device for delivering enough laser energy to each spot allowing the spot size to be made larger for faster treatment.
A further object of the present invention is to provide an improved laser apparatus that is simple to manufacture and assemble in an economical manner, and is cost effective for the user.
In accordance with the present invention, there is provided a laser apparatus for permanently, safely, and quickly removing a plurality of hair follicles, veins, capillaries or blood vessels from the skin of a patient; including patients with dark skin. The laser apparatus includes a housing having a single laser for emitting a series of pulses of coherent light energy having a pulse duration in the range of xc2xd to 10 ms; a multi-strand fiber optic bundle connected to the laser for transmitting a series of pulses of coherent light energy to the skin of a patient; and a sequence control device for controlling the laser to emit the series of pulses of coherent light energy sequentially, with a time delay between pulses being less than the thermal relaxation time of the hair and skin being treated, which typically is less than 20 milliseconds between the sequential pulses of the single laser. The laser apparatus includes a handpiece assembly for holding a section of the fiber optic bundle for directing the series of pulses of coherent light energy to the same spot of the patient""s skin to remove the plurality of hair follicles, veins, or capillaries, or blood vessels. In alternate embodiments, other optical delivery systems may be employed. These may include an articulated laser arm assembly, or a light path or pipe for a diode laser.
A method of removing hair or blood vessels from the skin of a patient using a laser apparatus having a single laser, a sequence control device and an optical delivery system, which includes the steps of controlling the single laser to sequentially emit a series of pulses of coherent light energy, transmitting the series of pulses of coherent light energy through the optical delivery system to the same spot on the skin of the patient, irradiating the same spot on the skin containing the hair or blood vessels with the sequential pulses of coherent light energy transmitted through the optical delivery system from the laser, and pulsing the laser at least two or more times through the optical delivery system at a wavelength in the range of 550 to 1200 nm, at a power level in the range of 1 to 20 Joules/cm2, at a pulse duration in the range of xc2xd to 10 milliseconds, having a pulse delay in the range of 1 to 20 milliseconds, and having a beam diameter on the treatment area in the range of 4 to 50 millimeters.
The new technology requires that a series of relatively low energy laser pulses be delivered in rapid succession with short delays between pulses to exactly the same area of the skin, so that the hair does not have time to dissipate the heat between pulses. Relatively low energy is delivered to the hair germinative apparatus using a series of short pulses from the single laser, with the pulses repeated at short intervals so the hair does not have time to dissipate the heat energy between pulses. For most patients, this means five or less low-energy (2 to 15 Joules/cm2) short duration (2 to 6 milliseconds) pulses, separated by short delays of less than 20 milliseconds, each with a large (e.g. 10 millimeters or greater) spot size. None of the currently-produced lasers are able to produce these results. The short delay between pulses is shorter than the thermal relaxation time of the hair and skin being treated, so the hair does not cool off between the pulses.
For example, short pulse duration lasers (with a pulse duration measured in nanoseconds) can repeat rapidly, but these are too short and are not suitable for optimal hair removal. All of the new hair removal lasers (ruby, alexandrite, diode) are long pulse lasers. Most of these recycle every 1000 milliseconds, with the fastest recycling every 200 milliseconds. The repetition rate that is necessary, however, must be a delay between pulses of less than 20 milliseconds. The new laser apparatus of the present invention is able to accomplish this new method.